blocks:

• SR-5112 Not correct function types in Swift4 (typeof)

Issue Description:

Swift should properly distinguish between single-tuple and multiple-argument function types.
But it isn't, as demonstrated below.
The following is the behavior of swift-DEVELOPMENT-SNAPSHOT-2017-06-05-a-osx (-swift-version 4):

func f(_ a: Int, _ b: Int) { print("\(a), \(b)") }
func g(_ tuple: (Int, Int)) { print("\(tuple)") }
f(1, 2) // 1, 2
g((1, 2)) // (1, 2)
// Working as expected.

// But:
print(type(of: f) == type(of: g)) // true (!?)

// Or, simpler put:
print(
    type(of: ((Int, Int) -> Int).self) ==
    type(of: (((Int, Int)) -> Int).self)
) // true

(Reported as requested by Mark Lacey here:
https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20170605/037013.html
)